Vibration absorption support



Feb. 5,` 1946.- c. s. ROBINSON VIBRATION ABSORPTION SUPPORT` Filed Deo. 211944 sheets-sheet 1 ATTORNEY Feb. 5, 1.946.

YC. S. ROBINSON VIBRATION ABSORPTION SUP-PORT- Filed Dec. 21, 1944 @sheets-sheet 2 INVENTOR (fc/z 5. /Po//vm/v,

y FJTORN EY Feb. 5, 1946.' c. s. ROBINSON VIBRATIGN ABSORPTION SUPPORT Filed Dec-.21, 1944 5 sheets-sheet s Patented F eb. 5, 1946 UNITED STATE y2,394,106ll oir-nce vrnA'rroNfABsoRPrIoN isProR'r' unitariamente-21; 1944-; seramos 5694185 somims. (o1. 24S-zaltively light compression' stressesv so that full ad vantage may bet'akeriV ofthe superior Vibration absorbing 'qualities V'characteristic of spongy'fmai ter-ials.- Other objects will 'become'apparent as" thefd'escriptionl proceeds.

The invention isparticularly useful" in mount#V ingapparatusin airplanes, cars and boats,where visiblevandl invisible"mechanical` vibrations 'are continuously present in thefvehicle itself under the -usual operatingconditions. InAsuch installa# tions"1 thewcontinuous vibrations` at certain'-f`re4` tions-a difficulty with prior'lmounts vvhich the present invention is adapted tojcorrect. Though primarily 'intended to meet the exacting conditions of airplane installations, this type ofmount can be'used to advantage under many otherL conditions Wherev Aobjectionable vibrations are" present. l

Referring now to tliedrawings'formingf part ofthis'specication, y Y

Fig. 1 is-aplan view,'lpartly` in section, of the" shock mount as seen from above.r

Fig. 2 is aside" elevation, partlyv inv section on the line 2-2 of Fig 1, showing end'views of the`rv various cylindrical cushions attached to -the` frames.

Fig. v3 is an-end elevation, partly in section,'on theline 3-3 of 'Fig'. 1, showing the cylindrical cushions ini side elevation, and the connecting frames.

Fig. 4 'is' a -crosslsection onr-` the :line 4 5-Bof Fig: '1,-' showing the cushions in lcross-section and on a larger scale.

Fig-"5 is a longitudinal crosssection on the line 5`5 of Fig.f1, showingV the cylindricalcushions and annular end cushions onl alarg'er scale. Fig'. 6 isa detail perspective viewof the rubber buierpa'ds or cushions'used.` s

Similar reference numerals referA to similar parts vvthruout the various vievv's` y Asishown insign, the mount is'generauy rec;

tangulariinform, andas will be-'seenfmore clearly in1 Fig:l 2and-1Fig-eg'ais composed' of 'a meursmary base'` frame I seoured to thel airplane or otherl supportingstructure,y a secondary frame 2 upon'which apparatus -to be protected'from vibra I tion may be carried, and an intermediate-'floating fra-me 3fconnected to the r'primzny framev I and to'tliejsecondaryf'frame"2j-by elastic cushions 4v and l4"- as` willV be described `in detailA later.

p The primary or base l frame I -iscomposed' 'of tvvoiparallel'trays 5 and 5 of similar construction connected at 'their Iends by 'cross channel' pieces 6k and'' to aform' a` relatively rigid rectangle, proportioned in generall accordingto the form oir tl'iejapparaftus to beI carried, so' that in someV cases itv 'mayA not1 befystrictlyf rectangular. The fsee-y ondaryirame" 2, tovvhich m'ayj'be' attached -such apparatus` as isi-to be protected from vibration, is 'constructed/'in*general similarly to the base fraine I,' though facingr it inI the opposite direction' and having various detailsV and points'fof attachment iof cushions `differently located; that is', the-secondary lframe is alsogenerally rectangular infsl'iapefand also `consists of tvvoparallelA trays "I` and"|j` connected: at their lends by "tvvo"y cross ychannel pieces 8 'and il'v to--forrnafrelatively rigidY rectangular structure 2.` A generali object offvthek deviceis to( connect thesecond'aryframe structure 2 -to"yth ej primary base frame I in such' a* mannerfas' to-minimizev the' transmission of vibrations -b-etweeni them. Experience -hasr'shown that -Irif'rrely` connecting two such y frames by Vrub-- ber cushionsdoes not* accomplish the desired result,v particularly asl regards harmonic peaks, 'and accordingly "under the present invention` the following" intermediate absorption structure is provided- This absorptionstru'cture*consists ofari intermediate `floating4rframe 3 "composed of parallel"v side vmembers@ "and '9" which fareA also'conne'cted acrosstheir endsby crosspieces'land I0" vto generally'f orrna` rectangular structure.v

but are elastically connected" at'certain points tothe -priinary baseframe I and elastically connectedatot-h'er points to the `secondary frame 2.

These"e1astic orv cushion connections will now be more particularly `described;

Referring to Fig.'2,it"will be seen that attached 'to Vthe primary Vbas`e"frarn`e I are'somewhat cylindricalfhousingsfl 2l y containing cylindrical absorptionA cushions! preferably made of spongerubber orsim'ilar lmaterial `of a porousgsp'ongy 'orielty ymature, having relatively large'area andlight" un'itloading as distinguishedV fromheavily com-'- The' sidem'embers 9 and"9arelocated between but pressed solid. rubber-the total volume oi the spongy cushions 4 being suiicient tosupport the load and still retain relatively, free elasticity. of

movement.fl Tw` of these cushions 4 are secured tothe tray 5 and two others Vsimilarly to the tray of .the sameY primary iframe l. Centrally thru Athesecushions 4 extend bolts I4 attached totheV intermediate floating frame 3. The cushionsare Y shown on a larger scale in Fig. 4 and Fig. 5.

yA similar setjofcushions 4' Vare contained in housings I2' secured to the secondary frame 2,

2,394,106 Y Y 4scribed the main pivotal bolts I4 andfl4' are Veffectively-stu*rounded on all sides by spongy cushioning material, both circumferentially and at the ends, 'so that the mountmay be placed in any position, vertically or horizontally, and still protect theV mounted apparatus from vibration.

and inY these cushions 4' yare contained similar bolts |4- which arealso attached to the intermediateoating framev 3, but the latter points of attachment are considerably different `in their distancefrom theY middle point or neutral axis of the frame 3, so that the-natural resonance pe-V Yriods at the bolts I4 and I4 areconsiderably dif-` ferent. f 'Ihis difference in spacing also permits a nesting o f the cushions in such a wayras not to increase the distance between theprimaryand.

secondary frames 'I and f2 butlittle more than it wouldrbe if .only one set of cushions were used.

' In manyins'tallationsYcompactness is highly desirable, iffnot essential.

' Byi referring'. to Fig. 3` and'particularly Fig. 5

' it will beseenfthat the cushions 4 .(and similarly 4') arenot Yonlytlfiick radially but also rather f long in an axial direction. 'This permits a relatively light loading of the cushioning material whichis thereby allowed to be flexible enough to permitfsome displacement of the central bolt vin all directions, andrals'o tilting of the bolt in-vie brating to positions out of parallel toits normal position if required. Though the mount i'sthus adaptedV to receive periodic vibrations of different types from all directions, it will be noted that th'e vibrations .are not likely to progress thru Ythe system without'encountering some part at which they are not in natural resonance-the resonance peridsabout the inner cushions being different from those'of the outer cushions. Moreover, the

-lightly compressed spongy 'materials do not have the,Y high resonance periods yfrequently found objectionable in solid cushions. 4

Whilenormally the load or incoming vibrations are Vtransverse tothe direction of the bolts I4, it

willlbe seen in Fig. 5 that cushions 20 are als()V provided near the ends ofthe bolts I4 to take care of thrusts or vibrations in axial directions relative tothe bolts I4. These cushions are held in cups 2| 4,formed on the ends of the housing I2,

Y Vwhilel the bolt ends carry complementary cups or.

The floatingV intermediate frame 3 plays an im-` portant part in reducing the vibrations and preventing harmonics, particularly as the designer is freeY to adjust th'e relative, locations ofV thesup'- porting bolts if certain harmonics become excessive.A

.While I have inthe foregoing described certain specific forms by way of YVexample,.it will be understood that theyl are merely for purposes of illustrationtomake clear the principles of the invention, which' is not limited to the particular formsshown, 'butis susceptible to various modifi'- bination of a primary base frame,a secondary load carrying frame, an" intermediate'V` floating. frame between the base frame and vthe secondaryV frame,`cylindrical cushions of spongy elastic material vmounted on the base iframe on the side facing the secondary frame atspacedlocations, cylindrical cushions of spongy elastic material f mounted onV the secondary frame on the side.

ringsf23 bearing on the other sides of the cushions e 2i). VThe cushions 20, like the cushions 4 and v4,

are thick and spongy. Adjustable'nuts 24 ontheends of the bolts I4 permit any desired initial degree of compression to be applied. Allrcushions i arefsuicientlyheld inv place by the mechanical structure' around them so that they need not be Y cemented or otherwise bonded to the metal. -This permits the ready replacementV of the cushions and also permits better control of the quality of the vibration absorbing material'.r Y Y g In normal operation the frames I, 2 and 3 do not Ytouch each other; and vibrations-attempting tY pass. between them arefintercepted by the sponge rubber cushions as described. However, rubber bulers are providedv at points Where the frames I, 2 and .3 might'contact each other under conditions of excessive vibration or shock, so'th'at the mount may not be damaged by abnormal conditions and also t0 avoid any possible metal to metal contact. i V

itwin .be ,noted that-in the cmistinaifm-de-` lfacing the base frame but at diierent'spaced 1ocations so as to avoid widening the space between the primary and secondary "frames and provide different h'armonicperiods, bolts extending approximately parallel to theplane of the base and passing axially thru the cylindrical cushions so as ytobe supported thereby, v said bolts being attached to the intermediatefloating frame, whereby vibrations entering the mount Vfrom the base frame must passV successively thru cylindrical cushions,v bolts, floatingV frame, and diierently spaced bolts and cylindrical cushions, before any Y residue rma:7 reach the secondary frame.

' 2. In a vibration absorbing mount, theY combination of a .primary base frame,a secondary load carryingl frame, angintermediate Yflo-ating Vframe between the base frame 'and the secondaryV frame, cylindrical cushions'v of spongyelastic material mounted on the base Aframe on the side facing the secondaryframe at spaced locations, cylindrical cushions of spongyjelastic material mounted on the secondary frame cn-they sidefac- Aing the base frame but at diierent spacedrlocations so as to avoidwidening the spacebetween the .primary and secondaryframes, and provide different harmonic periods, boltsA extending ap-v proximately parallelto the plane of the base and passingl axially thru the' cylindrical cushions so as to bfe supported-thereby, said bolts beingattached to the intermediatev Vfloating frame, and

buffer cushions limiting extreme vibrationof the intermediate frame, whereby vibrationsentering the mount Yfrom the baseframe mustvpass successively thru vcylindrical cushions, bolts,v iloating` frame, andl differently spaced bolts andfcylindrical cushions before any residue4 may reach the ysecondary frame. Y Y

3. In a vibration absorbing mount, thev combination of a primary base frame,ja secondary load carrying frame, (an intermediate VVfloating frame between the base frameV andthe secondaryframe, I

cylindrical cushionsA of spo-ngy elastic material mountedV on the baseframe onV the side-facing the secondary frame at spaced locations, cylindrical cushions of spongy elastic material mounted on the secondary frame on the side facing the base frame but at differently spaced locations so as to avoid widening the space-between the primary and secondary frames and provide different harmonic periods, bolts extending approximately parallel to the plane of the base and passing axially thru the cylindrical cushions so as to be supported thereby, said bolts being attached to the intermediate floating frame, heads on the bolts, and end thrust cushions of spongy elastic material between said heads andthe cylindrical vthe secondary frame at spaced locations, cylindrical cushions of spongy elastic material mounted on the secondary frame on the side facing the base frame but at differently spaced locations so as to avoid widening the space between the primary and secondary frames and provide different harmonic periods, bolts extending approximately parallel to the planeof the base and passing axially thru the cylindrical cushions so as to be supported thereby, said bolts being attached to the intermediate floating frame, heads on the bolts,

end thrust cushions of spongy elastic material between said heads and the cylindrical cushions previously mentioned, and buffer cushions limiting extreme vibration of the intermediate frame, whereby vibrations entering the mount'I from the base frame must pass successively thru cylindrical cushions, bolts, floating frame, and differently spaced bolts and cushions before any residue may reach the secondary frame.

5. In a vibration absorbing mount, the combi` nation of a primary base frame comprising a pair of parallel trays, a secondary load carrying frame comprising a pair of parallel trays, an intermediate `floating frame having parallel portions and located between the base frame and the secondary frame, cylindrical cushions of spongy elastic material mounted on the base frame on the side facing the secondary frame at spaced locations, cylindrical cushions of spongy elastic material mounted on the secondary frame on the side facing the base frame but at differently spaced locations so as to avoid widening the space between the primary and secondary frames and provide different harmonic periods, bolts extending approximately parallel to the plane of the base and passing axially thru the cylindrical cushions so as to be supported thereby, said bolts being attachedto the intermediate floating frame, heads on the bolts, end thrust cushions of spongy elastic material between said heads and the cylindrical cushions previously mentioned, and buffer cushions limiting extreme vibration of the intermediate frame, whereby Vibrations entering the mount from the base frame must pass successively thru cushions, bolts, floating frame, and differently spaced bolts and cushions before any residue may reach the secondary frame. CECIL S. ROBINSON.` 

